Date:	Tue, 19 Feb 2013 16:52:12 -0500
From:	Dave Jones <davej@...hat.com>
To:	Douglas Gilbert <dgilbert@...erlog.com>
Cc:	Tommi Rantala <tt.rantala@...il.com>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Jens Axboe <axboe@...nel.dk>, linux-scsi@...r.kernel.org,
	Sasha Levin <sasha.levin@...cle.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: WARNING: at drivers/ata/libata-core.c:5049
 ata_qc_issue+0x1c7/0x3a0()

On Tue, Feb 19, 2013 at 04:04:33PM -0500, Douglas Gilbert wrote:
 > On 13-02-19 01:37 PM, Tommi Rantala wrote:
 > > Hello,
 > >
 > > Hit this WARNING once while fuzzing the kernel with trinity in a qemu
 > > virtual machine as the root user.
 > >
 > > Does this make any sense? I have occasionally seen some ATA related
 > > troubles while fuzzing in a VM, but this warning is new to me.
 > >
 > > [  490.717030] WARNING: at
 > > /home/ttrantal/git/linux-2.6/drivers/ata/libata-core.c:5049
 > > ata_qc_issue+0x1c7/0x3a0()
 > > [  490.717030] Hardware name: Bochs
 > > [  490.717030] Pid: 2548, comm: trinity-child6 Not tainted 3.8.0+ #87
 > > [  490.717030] Call Trace:
 > > [  490.717030]  [<ffffffff81097b86>] warn_slowpath_common+0x86/0xb0
 > > [  490.717030]  [<ffffffff81097c75>] warn_slowpath_null+0x15/0x20
 > > [  490.717030]  [<ffffffff8150efd7>] ata_qc_issue+0x1c7/0x3a0
 > > [  490.717030]  [<ffffffff81516550>] ? ata_scsi_set_sense.constprop.13+0x30/0x30
 > > [  490.717030]  [<ffffffff815155c0>] ata_scsi_translate+0x120/0x190
 > > [  490.717030]  [<ffffffff81518f4e>] ? ata_scsi_queuecmd+0x2e/0x2d0
 > > [  490.717030]  [<ffffffff81519173>] ata_scsi_queuecmd+0x253/0x2d0
 > > [  490.717030]  [<ffffffff814e3e91>] scsi_dispatch_cmd+0x161/0x230
 > > [  490.717030]  [<ffffffff814e9fd4>] scsi_request_fn+0x544/0x580
 > > [  490.717030]  [<ffffffff813473a6>] ? cfq_dispatch_requests+0x56/0xb30
 > > [  490.717030]  [<ffffffff810f173a>] ? __lock_is_held+0x5a/0x80
 > > [  490.717030]  [<ffffffff81332112>] __blk_run_queue+0x32/0x40
 > > [  490.717030]  [<ffffffff8132d0ea>] __elv_add_request+0x10a/0x280
 > > [  490.717030]  [<ffffffff813391f6>] blk_execute_rq_nowait+0xb6/0xf0
 > > [  490.717030]  [<ffffffff810c0151>] ? __init_waitqueue_head+0x41/0x60
 > > [  490.717030]  [<ffffffff813392d8>] blk_execute_rq+0xa8/0x110
 > > [  490.717030]  [<ffffffff810f557e>] ? lock_release_non_nested+0xde/0x310
 > > [  490.717030]  [<ffffffff812fc1a4>] ? selinux_capable+0x34/0x50
 > > [  490.717030]  [<ffffffff812f8aa3>] ? security_capable+0x13/0x20
 > > [  490.717030]  [<ffffffff810a55d3>] ? ns_capable+0x53/0x80
 > > [  490.717030]  [<ffffffff8133f6c1>] sg_scsi_ioctl+0x2b1/0x3a0
 > > [  490.717030]  [<ffffffff8133fbc2>] scsi_cmd_ioctl+0x412/0x4a0
 > > [  490.717030]  [<ffffffff810f41d7>] ? __lock_acquire+0x957/0x1c20
 > > [  490.717030]  [<ffffffff81084adf>] ? kvm_clock_read+0x1f/0x30
 > > [  490.717030]  [<ffffffff81342d36>] bsg_ioctl+0x146/0x270
 > > [  490.717030]  [<ffffffff810f5b18>] ? trace_hardirqs_off_caller+0x28/0xd0
 > > [  490.717030]  [<ffffffff810f5bcd>] ? trace_hardirqs_off+0xd/0x10
 > > [  490.717030]  [<ffffffff810d552a>] ? local_clock+0x4a/0x70
 > > [  490.717030]  [<ffffffff810f1e98>] ? lock_release_holdtime+0x28/0x170
 > > [  490.717030]  [<ffffffff812fb640>] ? avc_has_perm_flags+0x1d0/0x2a0
 > > [  490.717030]  [<ffffffff812fb498>] ? avc_has_perm_flags+0x28/0x2a0
 > > [  490.717030]  [<ffffffff810f5b18>] ? trace_hardirqs_off_caller+0x28/0xd0
 > > [  490.717030]  [<ffffffff810f5bcd>] ? trace_hardirqs_off+0xd/0x10
 > > [  490.717030]  [<ffffffff811b5ff2>] do_vfs_ioctl+0x532/0x580
 > > [  490.717030]  [<ffffffff812fc7d3>] ? file_has_perm+0x83/0xa0
 > > [  490.717030]  [<ffffffff811b609d>] sys_ioctl+0x5d/0xa0
 > > [  490.717030]  [<ffffffff813571de>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 > > [  490.717030]  [<ffffffff81ca07e9>] system_call_fastpath+0x16/0x1b
 > > [  490.717030] ---[ end trace fce35d2b40bd0565 ]---
 > > [  490.810874] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
 > > [  490.812538] ata1.00: failed command: READ DMA
 > > [  490.813715] ata1.00: cmd c8/00:2c:00:01:00/00:00:00:00:00/e0 tag 0
 > > [  490.813715]          res 50/01:00:b0:16:04/00:00:00:00:00/a0 Emask
 > > 0x40 (internal error)
 > > [  490.817269] ata1.00: status: { DRDY }
 > > [watchdog] 333615 iterations. [F:326712 S:6891]
 > > [watchdog] kernel became tainted! Last seed was 71022097
 > > [  491.266158] ata1.00: configured for MWDMA2
 > > [  491.267358] ata1: EH complete
 > > child 2548 exitting
 > > child 2492 exitting
 > > child 2500 exitting
 > > [2351] Bailing main loop. Exit reason: kernel became tainted
 > > [2350] Watchdog exiting
 > >
 > > Ran 333617 syscalls. Successes: 6892  Failures: 326714
 > 
 > Looks like some application is using the deprecated
 > SCSI_IOCTL_SEND_COMMAND ioctl via a bsg node to send
 > a SCSI ATA PASS-THROUGH command tunnelling a ATA READ
 > DMA command.
 > 
 > Looking for something positive to say: only a very skilled
 > professional tester could come up with such a mismatch.
 
Unless Tommi has local modifications, what trinity does with sys_ioctl
is incredibly naive compared to some of the other syscalls.
It's a miracle it managed to pair an fd from a /dev node that understands
this ioctl with this set of arguments tbh.

The actual code it uses for fuzzing SG_IO looks like this..
https://github.com/kernelslacker/trinity/blob/master/ioctls/scsi-generic-sgio.c
It's not code I'm particularly proud of, it could be a lot more clever
than what it's currently doing, which is why I'm surprised it's having
positive results.

 > Is this a recent kernel (linux-2.6 shown in path)? Processes
 > using the SCSI_IOCTL_SEND_COMMAND ioctl now get a yellow flag
 > in the logs.

The trace shows 3.8.0+

	Dave

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